Animal-01-Naturalists-Sep-10-2.pdf

ZOOLOGY Lecture 1: Sept 10 The science of Zoology and the early naturalists 1 E.O. Wilson coined the term “biodiversity” Within animals, how do we understand the huge variation in biodiversity of form and function? How can we make sense of all of it? 2...

ZOOLOGY Lecture 1: Sept 10 The science of Zoology and the early naturalists 1 E.O. Wilson coined the term “biodiversity” Within animals, how do we understand the huge variation in biodiversity of form and function? How can we make sense of all of it? 2 1  To make sense of it all: Zoology uses the scientific method: Observation 1859: Evolution by Question natural selection upon a lot of support New Hypothesis THEORY Prediction Wallace Darwin English naturalists Testing Reject Support 3 Evolution by natural selection or The survival of the fittest Wallace Time Darwin How did they develop the same theory? 4 2  Wallace went to the Amazonas river: Studied insect biodiversity and built a large collection of unknown bugs and other species and then… lost most of it! Wallace 5 Wallace went to Indonesia: He was the first to note a drastic change in diversity: The Wallace line Wallace This is thee first of several contributions to a new discipline: Biogeography 6 3  Darwin traveled the world, starting in South America and including the Galapagos islands Darwin’s finches 1831-36: The Beagle voyage 7 Despite constant illness, he worked on these ideas: How can we explain species differences between mainland and Galapagos islands? How can we explain differences among islands? He borrowed ideas from other disciplines: 1831-36: Geology Economics The Beagle voyage 8 4  Lyell: The man behind Geological Gradualism The formation of mountains follows a gradual / uniform process of change, over a long period of time… This took many millions of years This took 26 years 9 Malthus: The man behind ideas on economics and human population growth How come human growth cannot be sustained over of time…? war disease 10 5  The proposal of the Theory was not an easy ride… especially for Darwin - The society was not ready for it - The church (Creationism) did not accept it The idea of a “family” connection between humans and apes was considered dangerous… 11 What about the scientific society? The re Two objections to the theory were raised: 1. The theory did not explain the origin of changes 2. The theory did not explain how changes are transmitted Darwin did not have an answer for these objections The answer came years later… Mendel: 1856-63: Research on chromosome heredity His findings were only recognized 35 yrs later 12 6  The five theories within Darwin’s theory: 1. Perpetual change 2. Common descent 3. Multiplication of species 4. Gradualism 5. Natural selection 13 PERPETUAL CHANGE 1 Living organisms are not constant or immutable, they change… BEST EXAMPLES: - The fossil record and - The effect of pesticides on insects This theory is widely accepted It rejects creationism and supports the other four theories 14 7  PERPETUAL CHANGE 1 Living organisms are not constant or immutable, they change An example of an evolutionary trend in the fossil record: Changes in horse anatomy Problems? In many groups, the fossil record is incomplete or biased 15 COMMON DESCENT 2 There is a common ancestor for all the living forms (current or extinct) This theory saw life as a branching tree… where large branches split in small (derived) ones… This was an appealing idea, but the issue was… it implied that humans descended from monkeys…. If this theory is correct, we can look for common / similar features to find relationships among animals And we can introduce two related concepts: Homology and Analogy 16 8  COMMON DESCENT 2 There is a common ancestor for all the living forms (current or extinct) Evidence of ancestry and relationships among groups? There is plenty: HOMOLOGY Fossils, molecular studies, etc. 17 COMMON DESCENT 2 There is a common ancestor for all the living forms (current or extinct) HOMOLOGIES: ANALOGIES: Characters derived from a Not from a common ancestor; common ancestor independent origin Differences between homologies Similarities between analogies come from Divergent evolution come from Convergent evolution 18 9  COMMON DESCENT 2 There is a common ancestor for all the living forms (current or extinct) Homologies allow us to explore ancestry and relatedness among animal groups. It also let us organize groups in a hierarchical way or Cladogram: CLADOGRAM: A nested hierarchy of groups in a branching diagram It tells when groups are related And how closely related Common characteristics 19 Coming up: The other three theories within the evolution theory 20 10